This invention relates to an occupant restraint system and, in particular, to an occupant restraint system having an air bag cushion with a vent.
Occupant restraint systems having air bag cushions are well known. During an impact of a predetermined severity, a restraint control module signals the inflator to inflate an air bag cushion to protect an occupant. There are times, however, when the air bag cushion inflates to a higher pressure and creates a larger force than desired or needed such as when the vehicle occupant is out of position or properly belted or when the collision is of a lesser severity.
Various solutions have been developed to decrease the internal pressure inside the air bag cushion by venting the gas inside the air bag cushion. Automatic vents have been installed on air bag cushions that open when a certain predetermined internal pressure has been reached. One example of such a vent is disclosed in U.S. Pat. No. 5,219,179, issued to Eyrainer et al. In Eyrainer, a predefined relief opening is designed to tear at a predetermined internal air bag pressure to provide damping action. However, other factors, such as a small-statured, buckled, or an out-of-place occupant, may require venting the air bag cushion at a pressure lower than the predetermined pressure of the automatic relief opening and in a more time-controlled manner or fashion. Further, the predetermined relief opening can only open in a set manner creating limited air bag geometries and internal pressures regardless of what the optimum air bag geometry would be for the particular occupant and crash conditions.
Accordingly, there is a need to provide an air bag cushion that is capable of venting depending on factors such as whether the occupant is buckled, the size and position of the occupant, and the severity of the crash, and that is able to produce multiple air bag cushion geometries and/or internal pressures.
Accordingly, it is an object of this invention to provide a vehicle occupant restraint system having an air bag cushion venting system that vents based on factors other than a predetermined internal air bag cushion pressure.
It is another object of this invention to employ an air bag cushion venting system that can provide time-dependent venting at strategic locations and instances in the crash event.
It is a further object of this invention to provide an air bag cushion venting system that produces variable air bag cushion geometries and controlled internal pressures to accommodate different vehicle occupants under variable conditions.
Accordingly, this invention features an air bag deployment system for a vehicle having an air bag cushion having at least one pyrotechnic vent, an inflator in communication with the air bag cushion for inflating the air bag cushion, at least one sensor, and a restraint control module electrically connected to the pyrotechnic vent and the at least one sensor. The restraint control module being operative to receive and analyze a signal from the at least one sensor and to signal the pyrotechnic vent to deploy, thereby allowing gas to vent from inside the air bag cushion.
These and other objects of the invention will be more readily apparent upon reference to the following detailed description.